It is sometimes required to have a hollow metal member with a thicker gauge (wall thickness) at a relatively small portion of one end or both ends, of the member while the majority of the length of the member between the ends can be a second, thinner, gauge. For example, rear axles in front wheel drive passenger vehicles are typically manufactured from a hollow tubular metal member which is formed into the required configuration in a press. While the axle requires a given wall thickness, for example three millimeters, along most of its length, the end portions of the axle can require an increased wall thickness, for example four and a half millimeters, to allow them to be affixed, by welding, to the wheel hub structures.
Rather than employ a feedstock member having the greater wall thickness (e.g. four and a half millimeters) along its entire length, (which would increase material costs and the weight of the member) it is known to employ a feedstock member having the smaller wall thickness (e.g. three millimeters) and to upset, or bulge, the ends of the feedstock member to obtain the necessary larger wall thickness required at the ends of the axle.
Conventionally, upsetting involves heating the end portions of the hollow member to place the material in a malleable state and then longitudinally compressing the member to deform it, increasing the wall thickness (gauge) of the hollow member in the treated area while decreasing its length.
While hot upsetting provides an advantage in that localized areas of increased gauge can be created, it does suffer from some disadvantages. In particular, hot upsetting must be performed at a separate manufacturing station where the ends of the hollow member can be heated and compressed and this increases the manufacturing time for the finished part, as well as the increasing the capital costs associated with providing a separate upsetting station and increasing the operating costs associated with operating the heaters for the upsetting operation.
Further, the heating required for hot upsetting requires a heating and cooling cycle for the upset portions of the hollow member and this heating and cooling cycle alters the properties of the hollow member in the upset areas. This typically necessitates that the upset areas be subsequently treated to harden the upset areas, adding a further process expense.
It is desired to have a method and system for upsetting at least one end portion of a hollow member which does not require the heating of the hollow member.